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Although various forms of functional metrics have become dominant for economic studies and are also widely used for quality studies, there are a number of other measures and metrics used in the software world that are completely detached from functional metrics.
As with the section on functional metrics, short discussions of these other approaches will be discussed here. For actually learning to use the approaches, full text books or courses by expert practitioners are recommended. Also recommended are web searches using the names of the metrics as keywords in the search argument. Some of the interesting nonfunctional metrics applied to software include, in alphabetical order: